1. Field of the Invention
This disclosure relates to differential protection systems. More particularly, this disclosure includes systems and methods for providing line current differential protection utilizing an external time reference when the external time reference is temporarily unavailable.
2. Description of the Related Art
Line current differential protection systems generally rely on proper handling and synchronization of data communicated between terminals of a power apparatus. A line current differential function responds to a sum of currents within a zone of protection. Thus, line current differential protection systems use current values that may be measured at different line terminals synchronized to a common reference base. Data synchronization may include, for example, channel based synchronization or external time reference based synchronization.